A conventional connector includes a screw type connector in which electrical cables are connected on the same shaft center through a screw (see JP2002-237348A). In the screw type connector, since it is required to rotate a plug or a socket many times in order to connect the cables, connection operation takes labor, and operability is low. Also, a wide operation space is required, and consequently the connector has a low integration density. Further, for securing a predetermined waterproof property or reliability of electrical connection, a predetermined fastening torque is always required. However, in the above screw type connector, the fastening torque may be loosened due to application of microvibration and therefore, torque control is always required. Accordingly, maintenance takes labor.
On the other hand, as a connector that solves the above problems, for example, there is a so-called bayonet type connector (See JP2001-52821A). However, the bayonet type connector cannot be connected to the screw type connector. Therefore, to improve connection operability and maintenance property, it is necessary to exchange the entire plug and socket of the screw type connector for those of the bayonet type connector, which is wasteful.